In a control system, actuators driven by hydraulic or pneumatic fluids might be used. As an example, a pneumatic actuator in a guided missile may be employed to move air vane control surfaces, or jet vane control surfaces, or swivel nozzles. A valve, such as a solenoid ball valve, controls the fluid flow to the actuator control chamber for work on the large area piston of a dual piston design or the large area, low pressure side of a single piston. The solenoid ball valve used for this purpose may be either an opened center valve or a closed center valve.
The opened center valve design has a large, constant gas flow rate. In a typical missile system the opened center valve design requires only one solenoid valve per actuator, whereas the closed center valve design requires two solenoids. However, the closed center valve requires much less gas to operate in a typical duty cycle of operation. The closed center valve has a performance deadzone causing some small signal performance degradation. The only gas flow requirement for the closed center valve is during piston displacement. Consequently, there is a trade-off in choosing between the valve system performances and the amounts of actuating fluid used during performance. Design requirements for use of such valve systems in guided missiles accentuate a need to minimize actuating fluid mass and storage volume.